World Academy of Science, Engineering and Technology International Journal of Electronics and Communication Engineering Vol:1, No:1, 2007 Emerging Standards - WiFi, ZigBee and WiMAX

Bhavneet Sidhu, Hardeep Singh, and Amit Chhabra

next big thing” predicted in wireless access is the introduction Abstract—The world of wireless telecommunications is rapidly of large Fixed Wireless Access cells using evolving. Technologies under research and development promise to technologies such as WiMAX. deliver more services to more users in less time. This paper presents the emerging technologies helping wireless systems grow from where we are today into our visions of the future. This paper will cover the

applications and characteristics of emerging wireless technologies: Metropolitan Area Network Wireless Local Area Networks (WiFi-802.11n), Wireless Personal 802.16 WiMAX Area Networks (ZigBee) and Wireless Metropolitan Area Networks (WiMAX). The purpose of this paper is to explain the impending 802.11n standard and how it will enable WLANs to support 802.11 WiFi emerging media-rich applications. The paper will also detail how 802.11n compares with existing WLAN standards and offer 802.15.4 ZigBee strategies for users considering higher-bandwidth alternatives. The emerging IEEE 802.15.4 (ZigBee) standard aims to provide low data rate wireless communications with high-precision ranging and localization, by employing UWB technologies for a low-power and low cost solution. WiMAX (Worldwide Interoperability for Access) is a standard for wireless data transmission covering a range similar to cellular phone towers. With high Fig. 1 Types of wireless access performance in both distance and throughput, WiMAX technology could be a boon to current Internet providers seeking to become the In effect, most of these wireless technologies will not be leader of next generation wireless . This paper also islands in themselves, but will offer some interconnectivity explores how these emerging technologies differ from one another. between each other. All this will just help in creating a perfectly connected environment. So just think of it-the Keywords—MIMO technology, WiFi, WiMAX, ZigBee. weather, temperature and other information is being communicated by tiny sensors based on ZigBee, passing data I. INTRODUCTION over radio waves from one to another. At the end of the line, HE first thing an investor needs to determine is what is the data is picked up by hotspots created by WiMAX or WiFi. Ttruly an emerging technology. For the investor, an All these innovations are not a shot in the dark. Work is emerging technology is one that offers a relatively happening on most of these technologies to bring out undiscovered method to solve a daunting wireless problem in applications so that they really help everyone stay a cost-effective way. The methods or technology itself may be connected. Some of the technologies are already available, non-conventional, but emerging technologies that become while others might be available towards the end of this year or mainstream are typically more evolutionary than the beginning of the next year. Various revolutionary. This is because a technology cannot succeed by technology options are shown in Fig. 1. In the pages to itself – it must bring the whole sector with it. This paper follow, we will look at these wireless technologies and the presents an overview survey of emerging wireless applications they promise to make possible. technologies – 802.11n, 802.15.4 and 802.16. 802.11n is a recent extension of the popular 802.11a/b/g technology known II. WI-FI (WIRELESS FIDELITY) – 802.11N International Science Index, Electronics and Communication Engineering Vol:1, No:1, 2007 waset.org/Publication/11360 as WiFi. UWB on the other hand is standardized as IEEE Demand for wireless LAN hardware has experienced 802.15.4 for low power, low-data rate applications. This phenomenal growth during the past several years, evolving technology innovation called ZigBee will make it possible to quickly from novelty into necessity. Wi-Fi technology is most remotely monitor various types of sensors-for air- commonly found in notebook computers and Internet access conditioning, lighting, smoke alarms, and many more. “The devices such as routers and DSL or cable . The growing pervasiveness of Wi-Fi is helping to extend the Manuscript received on November 30, 2006. All authors are with Department of Computer Science & Engineering, technology beyond the PC and into consumer electronics Guru Nanak Dev University, Amritsar, India (e-mails: applications like Internet telephony, music streaming, gaming, [email protected], [email protected], and even photo viewing and in-home video transmission. [email protected]).

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These new uses, as well as the growing number of Uncontrolled, multipath distorts the original signal, making it conventional WLAN users, increasingly combine to strain more difficult to decipher and degrading Wi-Fi performance. existing Wi-Fi networks. Fortunately, a solution is close at MIMO harnesses multipath with a technique known as space- hand. The industry has come to an agreement on the division multiplexing. The transmitting WLAN device components that will make up 802.11n, a new WLAN actually splits a data stream into multiple parts, called spatial standard that promises both higher data rates and increased streams, and transmits each spatial stream through separate reliability. Though the specification is not expected to be antennas to corresponding antennas on the receiving end. The finalized before end of 2007, the draft is proving to be current 802.11n draft provides for up to four spatial streams, reasonably stable as it progresses through the formal IEEE even though compliant hardware is not required to support review process. [2] that many [2]. Doubling the number of spatial streams from A wireless LAN (WiFi) is a data transmission system one to two effectively doubles the raw data rate. There are designed to provide location-independent network access trade-offs, however, such as increased power consumption between computing devices by using radio waves rather than a and, to a lesser extent, cost. The draft-n specification includes cable infrastructure. Wi-Fi is meant to be used generically a MIMO power-save mode, which mitigates power when referring to any type of 802.11 network, whether consumption by using multiple paths only when 802.11b, 802.11a, 802.11g etc. The first 802.11b networks communication would benefit from the additional could move data at up to 11 megabits per second (Mbps). performance. The MIMO power save mode is a required Then came products using 802.11a, followed shortly feature in the draft-n specification. thereafter by 802.11g, each with maximum speeds of 54Mbps 3) Improved Throughput and Higher Data Rates and throughput of around 25Mbps. WLAN hardware built Another optional mode in the 802.11n draft effectively around 802.11g was quickly embraced by consumers and doubles data rates by doubling the width of a WLAN businesses seeking higher bandwidth. [1] The next Wi-Fi communications channel from 20 MHz to 40 MHz. The speed standard, 802.11n, will likely offer a bandwidth of primary trade-off here is fewer channels available for other around 108Mbps [2]. And because it will be an industry devices. In the case of the 2.4-GHz band, there is enough standard, n-compliant devices will be interoperable. room for three non-overlapping 20-MHz channels. Needless to say, a 40-MHz channel does not leave much room for other A. Characteristics of 802.11n devices to join the network or transmit in the same airspace. The emerging 802.11n specification differs from its This means intelligent, dynamic management is critical to predecessors in that it provides for a variety of optional modes ensuring that the 40-MHz channel option improves overall and configurations that dictate different maximum raw data WLAN performance by balancing the high-bandwidth rates. This enables the standard to provide baseline demands of some clients with the needs of other clients to performance parameters for all 802.11n devices, while remain connected to the network. allowing manufacturers to enhance or tune capabilities to accommodate different applications and price points. With TABLE I every possible option enabled, 802.11n could offer raw data MAJOR COMPONENTS OF DRAFT 802.11N [1] rates up to 600 Mbps. But WLAN hardware does not need to Feature Definition

support every option to be compliant with the standard. In the Better OFDM Supports wider bandwidth & higher code rate to current year, for example, most draft-n WLAN hardware bring maximum data rate to 65 Mbps available is expected to support raw data rates up to 300 Mbps Space-Division Improves performance by parsing data into [1]. In comparison, every 802.11b-compliant product support Multiplexing multiple streams transmitted through multiple antennas. data rates up to 11 Mbps, and all 802.11a and 802.11g Diversity Exploits the existence of multiple antennas to hardware support data rates up to 54 Mbps. improve range and reliability. Typically employed 1) Better OFDM when the number of antennas on the receiving end is higher than the number of streams being In the 802.11n draft, the first requirement is to support an transmitted. OFDM implementation that improves upon the one employed MIMO Power Save Limits power consumption penalty of MIMO by in the 802.11a/g standards, using a higher maximum code rate utilizing multiple antennas only on as-needed and slightly wider bandwidth. This change improves the basis. International Science Index, Electronics and Communication Engineering Vol:1, No:1, 2007 waset.org/Publication/11360 40 MHz channels Effectively doubles data rates by doubling channel highest attainable raw data rate to 65 Mbps from 54 Mbps in width from 20 MHz to 40MHz. the existing standards [2]. Aggregation Improves efficiency by allowing transmission 2) MIMO Improves Performance bursts of multiple data packets between overhead One of the most widely known components of the draft communications. Reduced Inter-frame One of several draft-n features designed to specification is known as Multiple Input Multiple Output, or Spacing (RIFS) improve efficiency. Provides a shorter delay MIMO [2]. MIMO exploits a radio-wave phenomenon called between OFDM transmissions than in 802.11a or multipath: transmitted information bounces off walls, doors, g. Greenfield Mode Improves efficiency by eliminating support for and other objects, reaching the receiving antenna multiple 802.11a/b/g devices in an all draft-n network. times via different routes and at slightly different times.

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TABLE II wirelessly to the Internet from their computers and portable COMPARISON OF THE PRIMARY IEEE 802.11 SPECIFICATIONS gaming devices or use the network to compete with others 802.11a 802.11b 802.11g 802.11n in the home. • Network attached storage: A growing application that Standard July 1999 July 1999 June 2003 Not yet Approved ratified demands all that 802.11n has to offer high data rates as well as range and reliability is Network-Attached Storage, or Maximum 54 Mbps 11Mbps 54 Mbps 600 Mbps NAS. NAS has become popular in the enterprise as an Data Rate inexpensive, easy-to-install alternative for data backup. Modulation OFDM DSSS or DSSS or DSSS or More recently, NAS is taking hold in small offices and even CCK CCK or CCK or some homes, as users want to safeguard their growing OFDM OFDM digital photo albums from hard drive failure, and as the RF Band 5 GHz 2.4 GHz 2.4 GHz 2.4 GHz or price of self-contained NAS backup systems falls well 5 GHz below $1,000. New, more exciting applications for NAS are emerging, such as video storage centers that demand Number of 1 1 1 1,2,3, or 4 reliable, high-bandwidth connections to stream prerecorded Spatial Streams TV shows, music videos and full-length feature films to televisions and computers throughout the house. Channel 20 MHz 20 MHz 20 MHz 20 MHz or • Transferring large files such as prerecorded TV shows Width 40 MHz from a personal video recorder onto a notebook computer or for viewing outside the home takes B. Applications of 802.11n planning and patience on an older WLAN. Fig 2 compares the time it would take to transfer a 30-minute video file. At Because it promises far greater bandwidth, better range, and the best data transfer rate, it would take 42 minutes to copy reliability, 802.11n is advantageous in a variety of network the file using 802.11b, and less than a minute with a two- configurations. And as emerging networked applications take antenna draft-n client. hold in the home, a growing number of consumers will come

to view 802.11n not just as an enhancement to their existing network, but also as a necessity. Some of the current and emerging applications that are driving the need for 802.11n are listed below: • Voice over IP (VoIP): VoIP is mushrooming as consumers Fig. 2 Time (Best Case) to Transfer 30-Minute Video and businesses alike realize they can save money on long-

distance phone calls by using the Internet instead of traditional phone service. An increasingly popular way to III. ZIGBEE – 802.15.4 make Internet calls is with VoIP phones, which are battery- powered handsets that typically connect to the Internet with ZigBee is one of the newest technologies enabling Wireless built-in 802.11b or 802.11g. Telephony does not demand Personal Area Networks (WPAN). ZigBee is the name of a high bandwidth, although it does require a reliable network specification for a suite of high level communication protocols connection to be usable. Both 802.11b and 802.11g using small, low-power digital radios based on the IEEE consume less power than 802.11n in MIMO modes, but 802.15.4 standard. The technology is intended to be simpler single-stream 802.11n may become prevalent in VoIP and cheaper than other WPANs such as . ZigBee phones. VoIP phones can benefit today from the increased protocols are intended for use in embedded applications range and reliability of a draft-n access point. requiring low data rates and low power consumption. Though • Streaming video and music: As with voice, streaming WPAN implies a reach of only a few meters, 30 feet in the music is an application that requires a highly reliable case of ZigBee, the network will have several layers, so connection that can reach throughout the home. Millions of designed as to enable intrapersonal communication within the network, connection to a network of higher level and

International Science Index, Electronics and Communication Engineering Vol:1, No:1, 2007 waset.org/Publication/11360 consumers are building libraries of digital music on their personal computers by ripping their CD collections and ultimately an uplink to the Web. buying digital recordings over the Internet. In addition, Importance of Zigbee growing numbers are streaming music directly from the There are a multitude of standards that address mid to high Internet. Though higher bandwidth is not absolutely data rates for voice, PC LANs, video, etc. However, up till necessary, the additional range and reliability that draft-n now there hasn’t been a wireless network standard that meets offers may be better suited to streaming music than older- the unique needs of sensors and control devices. Sensors and generation WLAN hardware. controls don’t need high bandwidth but they do need low • Gaming: Gaming is an application that increasingly is latency and very low energy consumption for long battery making use of home WLANs, whether users connect lives and for large device arrays. There are a multitude of

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proprietary wireless systems manufactured today to solve a 1) Low power consumption, with battery life ranging from multitude of problems that also don’t require high data rates months to years. but do require low cost and very low current drain. 2) Maximum data rates allowed for each of the frequency The ZigBee Alliance is not pushing a technology; rather it bands are fixed as 250 kbps @2.4 GHz, 40 kbps @ 915 is providing a standardized base set of solutions for sensor and MHz, and 20 kbps @868 MHz. control systems. To allow vendors to supply the lowest 3) High throughput and low latency for low duty-cycle possible cost devices the IEEE standard defines two types of applications (<0.1%). devices: full function devices (FFD) and reduced function 4) Channel access using Carrier Sense Multiple Access with devices (RFD) [4]. An IEEE 802.15.4/ZigBee network Collision Avoidance (CSMA - CA). 5) Addressing space of up to 64 bit IEEE address devices, requires at least one full function device as a network 65,535 networks. coordinator, but endpoint devices may be reduced 6) 70-100m range. functionality devices to reduce system cost. 7) Low cost (device, installation, maintenance). Low cost to The ZigBee Standard has evolved standardized sets of the users means low device cost, low installation cost and solutions, called ‘layers'. [4] These layers facilitate the low maintenance. ZigBee devices allow batteries to last features that make ZigBee very attractive: low cost, easy up to years using primary cells (low cost) without any implementation, reliable data transfer, short-range operations, chargers (low cost and easy installation). ZigBee’s very low power consumption and adequate security features. simplicity allows for inherent configuration and Network and Application Support layer: The network layer redundancy of network devices provides low maintenance. has been designed to allow the network to spatially grow 8) High density of nodes per network: ZigBee’s use of the without requiring high power transmitters. The network layer IEEE 802.15.4 PHY and MAC allows networks to handle also can handle large amounts of nodes with relatively low any number of devices. This attribute is critical for latencies. The APS sub-layer's responsibilities include massive sensor arrays and control networks. maintenance of tables that enable matching between two 9) Fully reliable “hand-shaked” data transfer protocol. devices and communication among them, and also discovery, 10) Different topologies like: star, peer-to-peer, mesh the aspect that identifies other devices that operate in the B. Applications of ZigBee operating space of any device. ZigBee networks consist of multiple traffic types with their : The IEEE 802.15.4 physical layer own unique characteristics, including periodic data, accommodates high levels of integration by using direct intermittent data, and repetitive low latency data. The sequence to permit simplicity in the analog circuitry and characteristics of each are as follows: enable cheaper implementations. • Periodic data – usually defined by the application such as Media access control layer: The IEEE 802.15.4 media a wireless sensor or meter. Data typically is handled using access control layer permits use of several topologies without a beaconing system whereby the sensor wakes up at a set introducing complexity and is meant to work with large time and checks for the beacon, exchanges data, and goes numbers of devices. to sleep. • Intermittent data – either application or external stimulus User-defined Application Profiles defined such as a wireless light switch. Data can be ZigBee defined Object Layer handled in a beaconless system or disconnected. In disconnected operation, the device will only attach to the network when communications is required, saving significant energy. • Repetitive low latency data – uses time slot allocations Network and Application Support Layer such as a security system. These applications may use the guaranteed time slot (GTS) capability. GTS is a method IEEE Media Access Control Layer of QoS that allows each device a specific duration of time as defined by the PAN coordinator in the Superframe to do whatever it requires without contention or latency. IEEE Physical Layer

International Science Index, Electronics and Communication Engineering Vol:1, No:1, 2007 waset.org/Publication/11360 For example, an automatic meter reading application Fig. 3 IEEE 802.15.4 / ZigBee Stack Architecture represents a periodic data traffic type with data from water or

gas meters being transmitted to a line powered electric meter A. Characteristics of ZigBee and passed over a powerline to a central location. Using the ZigBee is poised to become the global control/sensor beaconing feature of the IEEE standard, the respective network standard. It has been designed to provide the Reduced Function Device (RFD) meter wakes up and listens following features: [3] for the beacon from the PAN coordinator, if received, the RFD requests to join the network. The PAN coordinator accepts the request. Once connected, the device passes the meter information and goes to sleep. This capability provides

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for very low duty cycles and enables multi-year battery life. WiMAX also makes ubiquitous Internet access possible. Intermittent traffic types, such as wireless light switches, WiMAX, operating at comparable distances as cellular connect to the network when needed to communicate (i.e. turn phones, can be installed on cellular towers and allow Internet on a light). For repetitive low latency applications a data access in as many places as cellular phone access. This guaranteed time slot option provides for Quality of Service adds a new dimension to what Internet access providers can with a contention free, dedicated time slot in each super frame offer: a broadband connection that a person can take with that reduces contention and latency. Applications requiring them when they travel. timeliness and critical data passage may include medical alerts WiMAX Forum was formed in April 2001, to promote and security systems. In all applications, the smaller packet conformance and interoperability of the standard IEEE sizes of ZigBee devices results in higher effective throughput 802.16. The forum was formed solely for development & values compared to other standards. ZigBee networks are promotion of devices supported by the 802.16 standard. In primarily intended for low duty cycle sensor networks (<1%). September 2004, Intel introduced initial samples of a WiMAX A new network node may be recognized and associated in chipset, named Rosedale. has plans to ship WiMAX about 30 ms. Waking up a sleeping node takes about 15 ms, as devices for use in the office and home by 2007. [5] does accessing a channel and transmitting data. ZigBee The IEEE 802.16 standard is versatile enough to applications benefit from the ability to quickly attach accommodate time division multiplexing (TDM) or frequency information, detach, and go to deep sleep, which results in low division duplexing (FDD) deployments and also allows for power consumption and extended battery life. both full and half-duplex terminals. WiMAX uses microwave radio technology to connect computers to the Internet. C. Comparison of ZigBee and Bluetooth WiMAX works very much like cell phone technology in that The bandwidth of Bluetooth is 1 Mbps; ZigBee's is one- reasonable proximity to a base station is required to establish a fourth of this value. The strength of Bluetooth lies in its ability data link to the Internet. Users within 3 to 5 miles of the base to allow interoperability and replacement of cables, ZigBee's, station will be able to establish a link using non line- of-sight of course, is low costs and long battery life. (NLOS) technology with data rates as high as 75Mbps. Users Most important in any meaningful comparison are the up to 30 miles away from the base station with an antenna diverse application areas of all the different wireless mounted for line-of-sight (LOS) to the base station will be technologies. Bluetooth is meant for such target areas as able to connect at data rates approaching 280Mbps [6]. wireless USB's, handsets and headsets, whereas ZigBee is meant to cater to the sensors and remote controls market and A. Characteristics of WiMAX other battery operated products. Technical aspects of 802.16a that are instrumental in In a gist, it may be said that they are neither complementary powering robust performance include following standards nor competitors, but just essential standards for characteristics: different targeted applications. The earlier Bluetooth targets • Power: Varies with band. Profiles from 100 Mw up to 2W interfaces between PDA and other device (mobile phone / • Configuration: P-P and P-MP Cellular etc.) and cordless audio applications. Bluetooth has • Spectrum: Initially 3.5 GHz licensed and 5.8 GHz addressed a voice application by embodying a fast frequency unlicensed bands hopping system with a master slave protocol. ZigBee has • Radio interface: OFDM, using 256 tones addressed sensors, controls, and other short message • Access Protocols: Downstream - TDM (Broadcast), applications by embodying a direct sequence system with a Upstream - TDMA with access contention star or peer-to-peer protocols. • Security via station authentication and encryption • Data rates variable with channel bandwidth 3.5 MHz in 3.5 I ORLDWIDE NTEROPERABILITY FOR IV. W MAX (W I GHz band, 20 MHz in 5.8 GHz band MICROWAVE ACCESS) – 802.16 • Actual realizable data rates are ~ 2b/Hz Yet another wireless network technology may have an • Maximum range ~2Km for indoor Non-LOS cellular impact over the next few years: 802.16, better known as service at 3.5 GHz WiMAX. The IEEE approved the 802.16 standards in June B. Applications of WiMAX International Science Index, Electronics and Communication Engineering Vol:1, No:1, 2007 waset.org/Publication/11360 2004 [5]. This technology supports speeds as high as 70Mbps and a range of up to 48 kilometers. WiMAX can be used for WiMAX will allow people to go from their homes to their wireless networking like the popular WiFi. WiMAX allows cars, and then travel to their offices or anywhere in the world, higher data rates over longer distances, efficient use of all seamlessly. [7] WiMAX can serve the business, residential bandwidth, and avoids interference almost to a minimum. and mobile segments. The applications in these areas are listed WiMAX can be termed partially a successor to the Wi-Fi below: protocol. Current technologists envision a WiMAX receiver in Residential users a person’s home, with a WiFi transmitter to serve in-home • Basic voice services, low cost domestic & international calls connections, and longer term having laptops and personal • Basic (dialup speed) to advanced (over 1Mbps) data devices capable of transmitting directly to WiMAX towers. connections

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• Bundled voice and data services Fi as its primary backhaul service of choice. WiMAX Business users promises to help corporations expand business, drive down • Basic data connectivity for small businesses costs, increase overall profitability, increase the quality of • Advanced data services to medium and large businesses service, and increase the number of users that connect to the • Feature-rich, low cost voice services (VoIP) Internet. Mobile users (mobile WiMAX only) • Data connectivity for mobile workforce REFERENCES • Data connectivity for international visitors [1] Introduction to Wi-Fi technology, Retrieved on September 24, 2006 from www.wi-fitechnology.com [2] Broadcom, 802.11n: Next-Generation Wireless LAN Technology, White V. COMPARISON OF WIRELESS TECHNOLOGIES Paper dated April 2006 [3] Homepage of 802.15 WPAN Task Group 4 (TG4), The use of wireless technologies is beginning to appear http://grouper.ieee.org/groups/802/15/pub/TG4.html similar to the initial development of the railways. Each [4] P. Kinney, ZigBee Technology: Wireless Control that Simply Works, technology seems to have a different “gauge” and White Paper dated 2 October 2003. compatibility issues seem to confuse the novice. The main [5] IEEE 802.16 and WiMAX: Broadband Wireless Access for Everyone, Intel Corporation, 2003. points of comparison of the three technologies that have been http://www.intel.com/ebusiness/pdf/wireless/intel/80216_wimax.pdf discussed in this paper are listed in table III. [6] Specifications of WiMAX. Retrieved on October 10, 2006 from http://wimax.com [7] Westech Communications Inc. on behalf of the WiMAX Forum, Can TABLE III WiMAX Address Your Applications? White paper dated October 24, COMPARISON OF EMERGING WIRELESS TECHNOLOGIES 2005. Technology WiFi - ZigBee WiMAX

802.11n Application Wireless Sensor Metro Area LAN, Internet Networks Broadband Internet connectivity Typical Range 100m 70-100m 50 km Frequency 2.4 GHz 2.4GHz 2-11GHz Range Data Rate 108 - 250Kbps 75Mbps 600Mbps Modulation DSSS DSSS QAM Network IP & P2P Mesh IP IT Network Yes No Yes Connectivity Network Infrastructure Ad-hoc Infrastructure Topology (Ad-hoc also possible) Access Protocol CSMA/CA CSMA/CA Request/Grant Key Attributes Wider Cost, Throughput, Bandwidth, Power Coverage Flexibility

VI. CONCLUSION This paper has presented an overview of emerging wireless technologies. 802.11n is viewed as the most likely contender for the home network backbone. ZigBee, on the other hand, is likely to make best use of its low-power and high-speed operation in short-range equipment interconnects, such as personal computers and portable equipment. ZigBee networks are primarily intended for low duty cycle sensor networks International Science Index, Electronics and Communication Engineering Vol:1, No:1, 2007 waset.org/Publication/11360 (<1%). 802.11n is viewed as being superior in maintaining compatibility with existing wireless LAN, while ZigBee is generally thought more likely to achieve lower levels of power consumption. Our vision of the future is that WiMAX will enable mobile broadband at an affordable price. This will be achieved through the adoption of WiMAX by a cellular provider seeking to make a jump to this disruptive technology. WiMAX is not expected to completely eliminate the Wi-Fi technology in the near future, but will be a complement to Wi-

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